One highly successful auxiliary power unit that has been used for the purposes just described is the Titan.RTM. manufactured by Solar Turbines Incorporated, San Diego, Calif. That unit, which is produced in many models for military and civilian fixed wing aircraft and helicopters, is a radial engine of the single shaft, integral bleed type. Compressed air needed for main engine starting and other purposes is tapped from a station between the compressor and turbine of the engine.
Among the several advantages of this type of gas turbine engine are: simplicity of design resulting in exceptional durability and reliability, low weight, operational flexibility in a variety of mechanical and climatic environments, low maintenance costs, and good servicability.